Experiencing a very strange RF problem.

[mikef]

Hey guys,

I have a very strange problem with my FM receiver in my Raptor 50. I have a JR8103 and a couple of JR 600FM receivers. My raptor has a JR 600FM and I have a fury extreme with a PCM10X.

My problem:

My servos glitch and go nuts whenever the engine idles, whenever I touch any metal part on the heli with another metal part (starter, hotshot, screwdriver), or whenever I get near it with a metal tool (I do not have to touch the heli). I have tried everything. I originally thought it was my TJ Pro but it was not. I started unplugging everything to see if I had a bad servo or other piece of equipment. Nothing helped. The engine does not have to be running for my servos to glitch.

I set up an experiment:

I have a spare 600FM receiver and I set it on my table top. I found an extra servo in my junk box and an extra battery pack. I hooked it all up and turn everything on while its on my table. Everything works as it should, but when I touch two metal objects within a foot of the receiver it goes nuts with the glitching.

I started playing with the transmitter at this point. I noticed that when my antenna is down, the gliching is much worse. When I put the antenna up, the glitching is totally eliminated as long as the transmitter is right there. I move the transmitter 50 ft away from the receiver with the antenna up. I notice that the glithing is minimal but still there a bit. I moved the transmitter 100ft away with the antenna up, and I can make the servos glitch enough to cause a heli to crash.

My question is: What is going on? How can two pieces of metal generate RF? And…how do I fix it?

My fury with the PCM10X is rock solid. I could not make it glitch. Should I buy a PCM for the raptor? Or will it just hide the glitching.

Everything is fully charged with brand new battery packs. I checked to see if there was any interference on my frequency and it is very clean. (I am a HAM guy so I have equipment to check it out with).

Any opinions, experiences, and advice welcome.

Thanks guys,

Mike

[WillJames]

I moved this to the JR forum because I know there are some people checking it. I left a shadow in the main forum to so it will atttract as many people as it can. Sounds like a freaky problem.

Is there any chance your TX is so close to your Heli it is overdriving it when youa re testing? (or whatever you call it) I can hold my 8103 right above the FM 549RX in my Ultra Stick and it will go nuts like that. If I move a few feet away it works great, and never a glitch in flight.

[capebob]

Mike,

I haven't had much luck with my JR 600s. They work great until they're crashed and then they seem to suffer serious range and selectivity problems. Having said that, all my helicopters that I've had on FM have exhibited your symptoms, but not as severely. One of my 600s that was showing some of these symptoms was removed from a helicopter and put in a plank. The plank nearly didn't survive. Only skill, cunning, and superior airman-ship (luck) saved the day. Range was much degraded. Because of this I've gone to all pcm except on my R 30 where I have a Hitec Super Slim. It has worked flawlessly for several years. I get a little tweak when removing my starter probe once in a while but it's not serous.

Or it could be what William said.

Bob

[pepper]

may be battery voltage, rubber gromments on the servos. or antenna on the rx may be cut somewhere??

pepper
GOD BLESS

[learjetcb]

i would switch to pcm. my rappy did the same thing with a fm receiver. the fm are ok for planks but i think there are to many multeble antenna wave lenths on a heli.what i mean here is that there is alot of metal in these helis that can pick up interferance. from other radio equipment that is not narrow banded. that can spalter and resonate on the the many peices of metal that are the right resonance for the splater so your receiver can pick it up being so close.most of the ham scaners don't pick up on this because the are well filtered. if you take a cb transmenter key it up on 26.19.50 witch is not legal. then go up to 27.28.50 and you can here every word the say withen a certain rang. (multybanding) all channels will do this to a certain extent depending on the radio and conditions. the farther you get away the less you here them but the cross chanel is still there. and if you have a anttena that is withen that resonace the problem is amplefied. as i said all the metal in your heli barings motor boom boom suports all anttenas at different frequency's. be sure to keep your antenna 1 inch away from all metal and servos.that is in the instructions i try to keep it as far away as possible. sorry for the SP errors i have to go in a hurry. any further ? just ask. :D

[learjetcb]

ps pcm has alot beter filtering

[mikef]

Thanks for all your input guys. I think I will buy a PCM receiver.

I have never seen this in a receiver before, but then again, I came from 10 yrs of flying wooden airplanes. The heli's are a different breed and teach me something every day. I'll keep the FM receivers for the zagi's and planes I have laying around.



Thanks again,
Mike

[learjetcb]

your welcome. glad to help. :D

[R- Rocks]

learjetcb I think the word your looking for is harmonic, you can have a second or third harmonic, thus wiping out your neighbors tv half a block away with that cb, some of that is bleed over, may be close proxcimity but you can have rf travel on the out side of your wires, ie a ferite choke. example cb voice entering your old phone line.